For certain endoscopic surgical procedures, for example arthroscopic knee surgery, surgical tools, such as cutters and burs, are commonly employed. Such tools typically include an elongate tubular outer member releasably fixable to the housing of a handpiece and containing an elongate tubular inner member movable therein by a motor in the handpiece. In many tools of this kind, the inner member is rotatable within the outer member and the distal end portion of the inner member defines a tissue working tip engagable with patient tissue through a window in the distal end portion of the tubular outer member. The tip comprises, for example, a bur, a shearing edge coactive with corresponding shearing edge in the outer member window, or other patient tissue working structure.
Tools of this type have normally been straight. However, in certain surgical procedures it is convenient if such a tool is bent at a location spaced intermediate the ends of the outer tubular member. A tool with an angled outer tubular member requires, however, that the inner tubular member be capable of flexing as it moves within the outer tubular member. This can be particularly difficult to achieve in an operational tool where the inner tubular member rotates within the outer tubular member, particularly at speeds at several thousand RPM.
Such rotary, bent (or angled or curved) tools are known.
For example, U.S. Pat. No. 5,437,630 (Daniel, et al.) assigned to Stryker Corporation, the present Assignee, discloses an inner member in which the flexible portion is not tubular but rather is, a central structure spaced radially inboard of the peripheral wall of the outer tubular member.
Examples of prior tools in which the flexible inner member is tubular include those disclosed in U.S. Pat. No. 4,646,738 (Trott) assigned to Concept, Inc. and U.S. Pat. No. 5,152,744 (Krause, et al.) assigned to Smith & Nephew Dyonics. Each employs an inner tubular member flexible portion of metal, at the bent portion of the outer tubular member. Such inner tubular members tend to be complex and expensive and it has proved difficult and may in extended use encounter problems of friction heating and metal fatigue.
U.S. Pat. No. 5,540,708 (Lim, et al.) assigned to Linvatec Corporation, discloses such a tool in which the flexible inner rotatable tubular member includes a metal tip, provided with a toothed window cooperable in rotative shearing relation with a corresponding shearing window in the distal end portion of the bent rigid outer tube. The inner tubular member further includes a proximal rigid plastic hub, the tip and hub being spaced by an elongate hollow tube of polymer material, for example PEEK (polyetheretherketone). However, in this particular prior tool, the structure of the joinder of the tip to the distal end of the polymer tube requires relatively complex machining operations on the adjacent ends of both and may limit the amount of force required to inadvertently pull the tip axially off the end of the tube.
Accordingly, it is an object of this invention to produce a bent tubular surgical tool having a movable (e.g. rotatable) inner tubular member and which overcomes certain difficulties of the prior art.